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    <p>If your tableview class provides ANY storage this will break. I would not recommend the path you're going down. But the correct method would be to use <code>object_setClass(tableView, [MyTableView class])</code>.</p> <p>Please make sure this is really what you want.</p> <p>Here is a small code-sample showing how this is a horrible idea.</p> <pre><code>#import &lt;objc/runtime.h&gt; @interface BaseClass : NSObject { int a; int b; } @end @implementation BaseClass @end @interface PlainSubclass : BaseClass @end @implementation PlainSubclass @end @interface StorageSubclass : BaseClass { @public int c; } @end @implementation StorageSubclass @end int main(int argc, char *argv[]) { BaseClass *base = [[BaseClass alloc] init]; int * random = (int*)malloc(sizeof(int)); NSLog(@"%@", base); object_setClass(base, [PlainSubclass class]); NSLog(@"%@", base); object_setClass(base, [StorageSubclass class]); NSLog(@"%@", base); StorageSubclass *storage = (id)base; storage-&gt;c = 0xDEADBEEF; NSLog(@"%X == %X", storage-&gt;c, *random); } </code></pre> <p>and the output</p> <pre><code>2011-12-14 16:52:54.886 Test[55081:707] &lt;BaseClass: 0x100114140&gt; 2011-12-14 16:52:54.889 Test[55081:707] &lt;PlainSubclass: 0x100114140&gt; 2011-12-14 16:52:54.890 Test[55081:707] &lt;StorageSubclass: 0x100114140&gt; 2011-12-14 16:52:54.890 Test[55081:707] DEADBEEF == DEADBEEF </code></pre> <p>As you can see the write to <code>storage-&gt;c</code> wrote outside the memory allocated for the instance, and into the block I allocated for random. If that was another object, you just destroyed its <code>isa</code> pointer.</p>
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    1. POObjective-C: How to change the class of an object at runtime?
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    1. COCool thanks. But, is it safe to set `self.tableView` in `UITableViewController` to a new instance of a custom subclass of `UITableView`?
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    2. COsay @JoshuaWeinberg, do you know if it'll be bad to use [Associative References](http://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/ObjectiveC/Chapters/ocAssociativeReferences.html) I know it's safe to use with categories (used it myself several times) but if the subclass need another variable, I think this will do the trick...
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    3. COI use them all the time, quite handy.
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